The partial amino acid sequences of rabbit and rat beta 2-microglobulins were securely established. Specific antibodies against rat beta 2-microglobulin were produced and with their use the membrane H-2 and TL antigens of mice will be studied. Partial amino acid sequences of human and dog alpha 2-microglobulin (retinol binding protein) were established. Further sequence studies will be done with cyanogen bromide fragments of this protein. Potentially serologically active peptides (HL-A, H-2, etc.) will be isolated from urine. Xenoantibodies against these proteins will be produced and tested for their serological specificities. The chemotactic activity of human beta 2-microglobulin will be tested. BIBLIOGRAPHIC REFERENCES: Poulik, M.D., Beta-2-Microglobulin, The Plasma Proteins, Second Ed., Vol. 1, F.W. Putnam, Ed., Academic Prees Inc., p. 433-454, 1975. Pious, D., Soderland, C., Weagant, S., and Poulik, M.D., Isolation of Stable and Unstable ("Suppressed") Beta-2-Microglobulin-Deficient Clones from a Lymphoid Cell Line, J. Immunology, 116:570, 1976.